Transplanting trilliums

There are number of large (~8" leaves) native trillium grandiflorum in the path of some construction on my property and I would like to move them so that they are not destroyed.
I've never tried to dig anything like this up; how deep do I need to go, and what do I need to know to keep from damaging them?
Thanks

Hello, and welcome to DG.

Trilliums have a corm, so you have to go deep enough to be sure you have that and roots on it. Mine are in humousy woods soil and seem to be deceptively shallow - the stems break off very easy and leave corm and roots behind. Probably you're going to want to go down a good 8 inches. Also make sure you take a good bit of their 'native' soil with you to help them settle in their new home.

Good luck with this, and let us know how it goes.